title: The C2H2 transcription factor regulator of symbiosome differentiation represses transcription of the secretory pathway gene VAMP721a and promotes symbiosome development in Medicago truncatula.
abstract: Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe regulator of symbiosome differentiation (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal symbiosome differentiation during nodule development. RSD is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial invasion zone. A tobacco (Nicotiana tabacum) retrotransposon (Tnt1) insertion rsd mutant produced nodules that were unable to fix nitrogen and that contained incompletely differentiated symbiosomes and bacteroids. RSD protein was localized to the nucleus, consistent with a role of the protein in transcriptional regulation. RSD acted as a transcriptional repressor in a heterologous yeast assay. Transcriptome analysis of an rsd mutant identified 11 genes as potential targets of RSD repression. RSD interacted physically with the promoter of one of these genes, VAMP721a, which encodes vesicle-associated membrane protein 721a. Thus, RSD may influence symbiosome development in part by repressing transcription of VAMP721a and modifying vesicle trafficking in nodule cells. This establishes RSD as a TF implicated directly in symbiosome and bacteroid differentiation and a transcriptional regulator of secretory pathway genes in plants.
authors.affiliation: The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
authors.forename: Senjuti
authors.initials: S
authors.lastname: Sinharoy
authors.forename: Ivone
authors.initials: I
authors.lastname: Torres-Jerez
authors.forename: Kaustav
authors.initials: K
authors.lastname: Bandyopadhyay
authors.forename: Attila
authors.initials: A
authors.lastname: Kereszt
authors.forename: Catalina I
authors.initials: CI
authors.lastname: Pislariu
authors.forename: Jin
authors.initials: J
authors.lastname: Nakashima
authors.forename: Vagner A
authors.initials: VA
authors.lastname: Benedito
authors.forename: Eva
authors.initials: E
authors.lastname: Kondorosi
authors.forename: Michael K
authors.initials: MK
authors.lastname: Udvardi
mesh_terms: D001483:Base Sequence; D002454:Cell Differentiation; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics*; D046913:Medicago truncatula / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D008954:Models, Biological; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009586:Nitrogen Fixation; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D055170:Plant Root Nodulation; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D055571:Secretory Pathway; D017422:Sequence Analysis, DNA; D016962:Sinorhizobium meliloti / Q000502:physiology; D013559:Symbiosis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors